karen lu is part of jan's oncology team and she's talked about metformen. many use it to control diabetes and when doctors started looking at it they saw something striking. >> when they looked at these large group of die bets, they found that those who were taking met fo ormen were having less cancers. >> it's fascinating. >> it is fascinating. >> dr. lu says tumors feed on insulin and it's lowered by the insulin levels so now she's launching a clinical trial to see if this really could be an effective treatment. >> the question is do we use it in patients once they have measurable disease and, you know, use it at that point -- at this point should we use it when people are in remission? we don't really know. >> what we do know is this. based 207b years of data, side effects are minor and rare and while cancer drugs cost tens of millions of dollars, metformin koufts like 10 cent as day. >> part of that is paying for failures. you see even if the medication is promising enough to be tested in humans, the vast majority those will not work. but that staggerin